Researchers at the Pasteur Institute in Paris have discovered that certain stem cells can stay alive in human corpses for at least 17 days after that person is declared dead. What were we saying the other day about the difficulty with defining death?

At what point does a person actually die? That depends on who you ask. To one person, it's the …
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The research, which is published in this week's issue of Nature Communications, is the first to show that groups of stem cells called myoblasts (which give rise to skeletal muscle) can survive for extended periods of time in remarkably unfavorable conditions. In the absence of blood flow, vital oxygen and nutrient supplies are sparse, if not entirely absent; previous research had suggested that stem cells could survive in cadavers up to two days after death — but beyond that? It seemed incredibly unlikely. Writes Live Science's Charles Choi:

Researchers had thought that dead bodies would be poor homes for any cells, lacking the oxygen and nutrients the body's cells need to stay alive. Nevertheless, histologist and neuropathologist Fabrice Chrétien at the Pasteur Institute in Paris and his colleagues were curious to see how long stem cells might keep ticking after a person died.

These stem cells in both dead mice and human corpses were dormant when discovered, with extraordinarily reduced metabolic activity, marking the first time scientists have found that stem cells were capable of such dormancy. The researchers suspect that chemicals given off after death, or the low levels of oxygen or nutrients in corpses, or a combination of all these factors, could have sent the stem cells into dormancy, helping them survive for weeks.

What's perhaps most remarkable about this research is that Chrétien and his colleagues didn't have access to any cadavers more than 17 days old. In other words, it's entirely possible that stem cells could survive even longer. Making sense of the mechanisms that make these "dormant" cells so resistant to undesirable conditions could have enormous implications for the way we store, study, and procure stem cells in the future.